Cloning, Expression, and Tobacco Overexpression Analyses of a PISTILLATA/GLOBOSA-like (OfGLO1) Gene from Osmanthus fragrans.

Zhanghui Zeng,Si Chen,Lilin Wang,Mingrui Xu,Min Wang,Zhehao Chen,Jiliang Pang

doi:10.3390/genes12111748

Abstract

GLOBOSA (GLO), a B-class MADS-box gene, is involved in floral organ determination but has rarely been studied in Osmanthus fragrans, which is a very popular ornamental tree species in China. Here, the full-length cDNA of a homologous GLO1 gene (named OfGLO1) was cloned from a flower bud of O. fragrans using the RACE technique. The OfGLO1 has a 645 bp open reading frame, encoding 214 amino acids. Similar to other PI/GLO proteins, OfGLO1 has two conserved domains, MADS MEF2-like and K-box, and a 16-amino-acid PI motif in the C terminal region. Our phylogeny analysis classified OfGLO1 as a PI-type member of the B-class MADS-box gene family. The qRT-PCR assay showed that the expression of OfGLO1 in O. fragrans was continuously upregulated from the tight bud stage to the full flowering stage but barely expressed in the pistils, sepals, and non-floral organs, such as root, leaf, and stem. The genetic effect of OfGLO1 was assayed by ectopic expression in tobacco plants. Compared with the wild-type, OfGLO1 transformants showed reduced plant size, earlier flowering, shorter stamens, and lower seed setting rates. Furthermore, some stamens were changed into petal-like structures. These findings indicate that OfGLO1 plays an important role in the regulation of flower development. This study improved our understanding of class B gene function in woody plants.

Highlights

Flowers of most higher-order plants consist of four whorls: sepals, petals, stamens, and carpels
The florescence of O. fragrans was divided into four stages: the tight bud stage, the early flowering stage, the full flowering stage, and the late flowering stage
GLO1 gene of O. fragrans [33], the primers were designed for PCR amplification

Summary

Introduction

Flowers of most higher-order plants consist of four whorls: sepals, petals, stamens, and carpels. Based on molecular and genetic studies in two model plants, Arabidopsis thaliana and Antirrhinum majus, Coen and Meyerowitz proposed a classical ABC model [1] to predict whether three classes of homeotic genes (encoding the A, B, and C functions) act alone or in combination to give rise to sepals, petals, stamens, and carpels. This prediction can be confirmed to some extent. Other models, such as ABCDE [3], tetramer [4], boundary attenuation [5], boundary slip [6,7], and BC bifunctional genes [8], were derived

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